Response of Plasmodium falciparum infections to pyrimethamine-sulfadoxine in Thailand.

The results of this study in Thailand indicate that the early response of falciparum infections to a single dose of pyrimethamine-sulfadoxine is influenced by the developmental stages of the parasite present at the time of treatment. Parasite clearance is slower when young rings predominate at the time of treatment. This should be taken into account when considering the clinical management of patients and the comparative efficacy of antimalarials in clearing parasites from the peripheral blood.

Specific DNA probe for the diagnosis of Plasmodium falciparum malaria.

Malaria can be diagnosed either by direct microscopic examination of blood smears, which is time consuming and requires expertise, or by immunological techniques, which are effective but do not distinguish between past and present infections. In this study, a simple procedure was developed for spotting lysed blood from infected patients directly onto nitrocellulose paper and identifying the malaria species on the basis of hybridization of parasite DNA with a species-specific probe. A genomic DNA library of Plasmodium falciparum was screened to detect clones containing DNA sequences that are highly repeated within the parasite genome.

Sensitivity to quinine and mefloquine of Plasmodium falciparum in Thailand.

Between 1982 and 1984 a regimen consisting of quinine and tetracycline was routinely used in Thailand to treat outpatients with microscopically confirmed falciparum malaria. Due to compliance problems associated with the 7-day multiple-dose regimen, there was a recrudescence rate of approximately 30%. Studies carried out in 1982 and 1984 in four areas of Thailand indicated that there was a significant decrease in the sensitivity of Plasmodium falciparum to quinine.

Use of the in vitro microtechnique for the assessment of drug sensitivity of Plasmodium falciparum in Sennar, Sudan.

In 1978, studies on the chloroquine sensitivity of Plasmodium falciparum were carried out in the district of Sennar, Sudan. The results of the in vivo tests showed parasites resistant at the RI level only, but the mean clearance time of trophozoites from the blood was higher than for strains found in many other areas of tropical Africa. The in vitro tests, using the microtechnique, indicated a lower sensitivity to chloroquine in the local P.